This research proposal will address the fundamental issue of how the interactions within the olivocerebellar system mature. Two general questions will be asked: 1) Are the sources of developmental differences in cerebellar and inferior olivary physiology a product of dynamic interactions within the olivocerebellar system? 2) Are the developmental differences completely dependent on neural maturation, or can they be changed by strengthening the differences in some areas and mitigating the differences in others? The experiments will use neurophysiology and pharmacology to elucidate the differences in somatosensory information processing between relatively immature rat pups (postnatal days 17-18) and relative mature rat pups (postnatal days 24-25). Development within the olivocerebellar system will be observed in the cerebellar cortex, the cerebellar deep nucleic, and the inferior olive. The development of interactions in the olivocerebellar cortex, the cerebellar deep nuclei, and the inferior olive. The development of interactions in the olivocerebellar system will be investigated by 1) examining the maturation of the inferior olive's influence on cerebellar neuronal activity, and 2) examining the influence that the cerebellum has on the inferior olive. This project may lead to a better understanding of the functional pathology associated with various developmental disorders that affect the nervous system including fetal alcohol syndrome, exposure to environmental toxins, and infantile autism.